The present invention pertains generally to the electromagnetic (EM) stimulation of combustion in internal combustion (IC) engines for achieving high efficiency and low emissions through the rapid combustion of very lean air-fuel mixtures. In particular, the improvement pertains to modifying the geometry of the combustion chamber principally by adding dielectric filled extensions ("wings") to the periphery of a standard piston engine combustion chamber for the purposes of lowering and controlling the EM operating frequency, as well as to improve the coupling, and the containment and stability of the EM energy with piston motion near engine top-dead-center, TDC. These improvements are achieved by exciting specific modes developed herein, preferably at UHF frequencies, and which use both the main combustion chamber and wings to achieve their desirable result.
The present approach to improve engine efficiency and lower emissions (necessary to meet emisson standards) is the computer controlled/catalytic converter water-cooled gasoline engine, and the diesel engine. The former is very expensive, complex and fuel inefficient, and the latter is very expensive, complex, heavy and has serious emission problems (soot and NOx). Variations of these two engine types, such as stratified charge and fast lean burn engines, are improved systems but still have the shortcomings of requiring high swirl to operate (which reduces efficiency through increased heat transference and air-pumping losses), computer controlled three-way catalytic converter operation, and conventional cooling systems. Most notable of these are the Honda CVCC engine, the May Fireball, and the Nissan Naps-Z engine. There is a great need for an engine that is highly fuel efficient, inexpensive, simple and clean.
An alternative approach to improving the IC engine is to design the engine to operate an extremely lean mixture (beyond that considered feasable or practical today), and to increase its flame speed, so that it can meet emission standards, and achieve high efficiency, through the combustion process itself. There is much prior art on improving ignition of very lean mixtures, with almost all of it pertaining to effecting air-flow characteristics and improving the ignition sparks.
This invention pertains mainly to electromagnetic means for improving combustion, and particularly for stimulating the burn so that the lean limit of flammability is extended and the flame speed is increased. It relates to U.S. Pat. Nos. 3,934,566 and 4,138,980, which disclose systems for improving combustion through EM stimulation, and to U.S. Pat. No. 4,297,983, which discloses a modification of the piston face used for exciting a microwave mode designated as the "spherical re-entrant".
However, the thrust of the present invention is to extend the periphery of the combustion chamber, to substantially lower and control the EM resonant frequency, and to excite principally EM modes which have zero, versus maximum, electric field in the center of the chamber. These modes allow the extended chamber resonance to be even more stable with piston motion, especially for ceramic coated combustion chambers.